Consumable glass fiber ingot mold liner



Sept. 18, 1956 N. J. GRANT CONSUMABLE GLASS FIBER INGOT MOLD LINER Filed July 25, 1954 INVENTOR NICHOLAS 3'. GRANT BY m ,MMW-

ATTORNEYS:

United States Patent CONSUMABLE GLASS FIBER INGOT MOLD LINER Nicholas J. Grant, Winchester, Mass., assignor to Lukens Steel Company, Coatesville, Pa., a corporation of Pennsylvania Application July 23, 1954, Serial No. 445,255

Claims. (Cl. 22139) This invention relates to the art of casting metal ingots by pouring of metal into molds and, more particularly, to improved means for facilitating the casting of steel ingots free from surface imperfections and defects.

It is appreciated throughout the steel industry that the surface defects and blemishes on cast steel ingots, as well as in other metal, result in poor surfaces in the subsequent rolled or forged product through the formation of scabs and slivers. Surging of the metal during top casting also results in a type of defect which can give poor surfaces, these defects frequently looking like veins or snakes on the ingot surface. Due to such bad surfaces, it is necessary either that the ingots be cooled to permit conditioning on the surface, which prevents direct rolling, or the ingots must be rolled directly in spite of such defects, in which latter case there is extensive conditioning of the rolled billet or bloom surface subsequently. Because of the prevalence of such surface defects directly associated with ingot pouring, some of the slabbing mills have made it a standard practice to scarf the entire surface of the plate, sheet or other ingots and this is done automatically since it is realized that defects of the above types exist on essentially all of the ingots.

Accordingly, it can be said without exaggeration that there is an extreme need to improve the ingot surface of cast ingots by avoiding the formation of splash and surging defects during top pouring. Also, it appears that no method has yet been devised which has accomplished this in spite of many efforts in this same direction. Such endeavors include pouring through steel funnels, pouring into tar coated molds, pouring into soot coated molds, and other devices, such as disclosed in U. S. Patents 2,273,543, Terrill, and 1,678,976, Durfee, wherein curtains or the like of metal similar to the metal being poured are employed as splash preventing liners.

The idea of putting a barrier or liner of some sort between the ingot mold wall and the metal stream entering the mold is, of course, the basic method available to everyone to prevent splashing, although not necessarily surging. In considering the properties of a material to be suspended in or attached to the inside of an ingot mold in the form of a liner or partition in spaced relation or abutting the interior surface of the mold, and for the purpose of preventing splashing and minimizing surging without damaging the ingot or the mold, the following characteristics should be kept in mind:

1. The barrier or partition should fuse or, in other words, the barrier should serve to prevent the splash from contacting the walls of the mold and to decrease or minimize the surging effects of the metals, and then melt away.

2. The barrier or liner should not leave a large amount of residue and a curtain of fiberglass, in this sense, is ideal in that the glass converts to a small quantity of fluid, liquid slag, which, because of its high fluidity, tends to stay in large lumps and therefore is not trapped in Patented Sept. 18, 1956 the ingot during pouring. These large silicate particles easily float out in the molten metal being poured.

3. The liner should be inorganic and have low vapor pressure, as it is undesirable to have gas generation which occurs from all carbonaceous products such as tar or soot. It must also have a low vapor pressure so that the material itself does not convert as a whole into a vapor which would then have an equivalent effect to a gas. Such would be free of water in any form and if gases are formed, or if vapors are formed, these can serve to generate blow-holes on the surface or just below the surface of the ingot.

4. The barrier material should be non-reactive. Most oxides and silicates are quite stable at high temperatures and therefore do not react with the metal itself to form other products.

5. The barrier should be a poor conductor of heat. When the metal splash hits a fiberglass curtain or liner, instead of freezing, as it does against the cold wall of an ingot mold, the particles stay in the molten form and simply fall back into the molten metal where they are assimilated without leaving localized defects. In the case of a metallic splash preventive device as disclosed in the U. S. Patents 2,273,543 and 1,678,976, even though such devices prevent the splash from striking the ingot mold wall, they nevertheless cause the splash particles to freeze, in which condition these particles are not readily assimilated by the ingot proper, giving a nonhomogeneous product.

6. The liner material should be relatively inexpensive and readily available and easy to install.

By this invention, a liner or partition having the above characteristics has been provided, the liner comprising glass fibers or fiberglass in one form or another, and in some instances may be bonded by a suitable binder. As is well known, fiberglass or glass fibers are available in many categories, such as in the form of a loose wool, as batts or mats, in which the fiberglass fibers are bonded with starch or with waterglass or other suitable binder, or even in the form of plastic-bonded or plastic-impregnated sheets. Initial experiments of the idea of using fiberglass in one form or another as a liner or barrier was only moderately successful with starch or waterglass utilized as the bonding agent and this was so due to the fact that the binder melted or burned out with such rapidity that a less than desired degree of protection against splashing and surging of the poured molten steel was achieved. However, the form of this invention which proved highly successful and is preferred comprises a liner of woven fiberglass cloth, since such is free of a binder and therefore cannot disintegrate due to the breakdown of the binder.

Therefore, it is an object of this invention toprovide an improved liner for casting ingots whereby the resultant ingot will be free of surface imperfections, defects, and blemishes.

It is another object of this invention to provide a liner for use in an ingot mold, said liner functioning to prevent splashing of the molten metal on the interior surface of the mold and to minimize surging.

Finally, it is another object of this invention to provide an ingot mold having suspended therein and abutting or spaced from the interior surface thereof a liner or barrier which is readily fusible with the molten metal and permits the casting of an ingot without defects or imperfections.

Other objects and advantages will be obvious from the following description, taken with the accompanying drawings, in which:

Figure 1 is a vertical sectional view showing the liner positioned within an ingot mold;

Figure 2 is a vertical sectional view similar to that of Figure l but illustrating the mold partly filled with molten metal;

Figure 3 is a vertical sectional view of a slightly modified form of the invention; and

Figure 4 is a detailed cross sectional view illustrating the preferred form of the liner of this invention.

Referring to the drawings in detail, the numeral 1 represents an ingot mold of any suitable configuration, such as of tubular or cylindrical form. Supported by means of spacer or suspension elements 3 within the mold 1 is a liner, barrier, or partition 2, this liner being illustrated as positioned or supported in the mold in spaced relation to the interior surface thereof and preferably being slightly elevated from the bottom surface 4 of the mold so that the molten metal may enter the entire interior surface of the mold. It is to be understood that any suitable type of suspension means 3 may be employed and, if desired, this suspension means may be made adjustable. Furthermore, instead of arranging the liner so that it is spaced from the interior of the mold, it may take the form as illustrated in Figure 3 wherein the liner abuts the interior surface of the mold. The parts illustrated on the drawing, such as the mold, are merely illustrative and it is apparent that many other shapes and forms may be utilized without departing from the scope of this invention.

As previously explained, the liner is made of fiberglass and may be of several forms, such as a mat or batt bonded by a suitable binder. However, woven fiberglass in the form of a curtain is preferred and fulfills best of all the requirements previously enumerated relating to preferred characteristics of a liner.

In operation, with the liner positioned as illustrated in Figures 1 and 2, the molten metal 5 enters the mold from a suitable pouring spout 6 and this metal strikes the bottom of the mold and splashes in all directions, some splashing continuing throughout the pouring due to the poured metal striking the molten metal positioned within the mold. The liner 2 prevents the splashing from striking the mold wall and from forming imperfections such as scabs or other defects on the surface of the ingot. Visual observation during the top pouring of ingots in which a fiberglass curtain had been installed, preferably of the woven type, indicated that the fiberglass melted away just at the contact surface With the metal as it rose in the mold and as illustrated in Figure 2. Splash particles, on striking the curtain or liner, simply fall back in a molten condition into the ingot and it was noted that, when heavy surging occurred, the Woven fiberglass curtain moved back against the wall by the force of the moving metal and thereby minimized defects produced by such surging action. Actually, when the fiberglass curtain was directly attached to the ingot mold wall, as in Figure 3, the splashing was eliminated in the same manner as when the liner was employed as in Figure 1 but surging was more effectively handled.

After a number of preliminary trials, it has been found that a single thickness of Woven fiberglass cloth which is 0.040 inch thick in wall cross section works best and is most satisfactory. Double thicknesses of this material did not give as good results as did a single thickness. Utilizing the single thickness of woven fiberglass as a curtain, the most recent results showed that of a large number of top-poured ingots cast, all were rolled directly. This is by far the best performance which was achieved in experiments in which many different types of splash preventative measures had been used. It must be realized, of course, that increasing the thickness of the fiberglass to too great an extent, double thickness or more, results in the formation of too much slag which may not be beneficial in that this large quantity of slag may be trapped between the metal and mold surfaces, giving rise to other defects. Similarly, it is to be realized that too thin a woven fiberglass cloth or fabric would be inelfective in that even the finer splash would burn through the-cloth. In particular, the much thinner cloth might even be damaged by the intense heat of the pouring stream as the stream passed the cloth on its downward movement to the bottom of the mold. For this reason, it was found that a thickness of about 0.02 to 0.06 inch is the ideal thickness to accomplish the intended purpose.

As previously stated the liner may be a mat of interengaged or heterogeneously arranged glass fibers bonded by a suitable binder, but it is preferred to employ a woven fabric comprising continuous yarns formed by glass fibers as shown in Figure 4 of the drawing.

The above description and drawings disclose several embodiments of the invention, as specific language has been employed in describing the several figures. It will, nevertheless, be understood that no limitations of the scope of the invention are thereby contemplated, and that various alterations and modifications may be made such as would occur to one skilled in the art to which the invention relates.

I claim:

1. An ingot mold comprising a vertically disposed hollow mold casing, said casing having its lower end closed and its upper end open, a fusible hollow vertically disposed liner having both ends open and a cross sectional configuration similar to that of said casing, said liner being suspended in said casing with its lower end spaced from the lower end of said casing to allow molten metal poured into said casing to reach the entire inner surface thereof, said liner comprising a fabric made up of glass fibers adapted to be fused by said molten metal.

2. A mold as defined in claim 1, wherein said fabric is woven.

3. A mold as defined in claim 1, wherein the liner has a wall thickness in the range of 0.02 to 0.06 of an inch.

4. A mold as defined in claim 1, wherein the liner is supported in substantially uniformly spaced relation to the wall of said casing.

5. An ingot mold comprising a vertically disposed hollow mold casing, said casing having its lower end closed and its upper end open, a fusible hollow vertically disposed liner having both ends open and a cross sectional configuration similar to that of said casing, said liner being suspended in said casing in substantially uniformly spaced relation to the side wall thereof and with its lower end spaced from the lower end of said casing to allow molten metal poured into said casing to reach the entire inner surface thereof, said liner comprising a fabric made up of glass fibers woven together and adapted to be fused by said molten metal, the thickness of the wall of said liner being in the range of 0.02 to 0.06 of an inch.

References Cited in the file of this patent UNITED STATES PATENTS 1,678,976 Durfee July 31, 1928 1,859,355 Crowther May 24, 1932 2,273,543 Terrill Feb. 17, 1942 2,631,344 Kennedy Mar. 17, 1953 FOREIGN PATENTS 626,906 Great Britain July 22, 1949 

